1. Field of the Invention
The invention relates to a device for securing objects, preferably inside closed buildings, especially for securing objects that belong to the inventory of an office.
The invention also relates to a device for detecting and storing signals that are emitted by a transmitter located on the object and that have a unique encoding for each object.
2. Related Technology
A device for securing issued tools or equipment is known from DE 200 11 952 U1, which disclosed a transponder using 128-bit information and containing data about the type of tool wherein, a consecutive serial number and information about the normal workplace is attached to each item of a set of tools. In this context, the normal workplace can be either a toolbox or a specific storage place, as long as this workplace has a stationary receiver for exchanging signals with the transponders that are attached to the tools. The receiver, in turn, is connected to a computer that allows the evaluation of the signals received by the receiver and emitted by the transponders attached in the toolbox or on the tools located at the workplace. Thus, at any point in time during the internal work procedures, the current status of the tools located in a specific toolbox or workplace can be displayed. In another embodiment of the device, a dedicated transponder is associated with each worker by means of which the toolbox belonging to the worker can be opened.
DE 197 45 953 A1 describes a device for automatically detecting and identifying a merchandise security label by means of a base station. The merchandise security label attached to the product to be secured comprises a transponder having an NF transmitting-receiving unit of its own that is used for communication with the base station. If, for example, a transponder enters the range of action of the electromagnetic field generated by the base unit, the base station transmits a control signal that is received by the transponder and that, in turn, causes the transponder to emit a response signal. This response signal is further processed by the base station and, in case of a successful checking, triggers a transmitting pulse at the base station that, in turn, is received by the transponder. This transmitting-receiving sequence can be used to integrate previously specified checking criteria which, if not observed, lead to the triggering of an alarm. In a preferred embodiment, the alarm signals of several transponders located in the range of action of the electromagnetic field of the base station are synchronized so as to ensure that the base station reliably recognizes a received alarm signal.
Another electronic anti-theft device is known from DE 38 07 936 A1. This publication discloses an especially preferred construction of a passive transponder that is combined with a barcode and whose dimensions are extremely small, whose receiver is coordinated with the double transmit frequency and that is thus insensitive to reflections of the fundamental wave of the transmitter. The stationary transmitting means is implemented either in the form of conventional transmitting-receiving means from the realm of high-frequency technology or in the form of array antennas employing stripline technology so that when the product identified by the transponder passes through the electromagnetic field generated by the stationary transmitting-receiving unit, the passive transponder is excited to emit radiation. The radiation emitted by the passive transponder can then be used to trigger an alarm signal.
A device for finding files is known from DE 100 33 557 A1. Here, signal transmitters in the form of transponders are attached to the files and the encoded signals that are transmitted by the transponders are detected by transmitting-receiving means that are preferably mounted on the ceilings and subsequently made available to a database for internal administration purposes. A central computer makes it possible to process the existing data records by means of an adapted administration routine in such a way that the current location of any given file from the stock of files can be ascertained at any time.
Various devices for the set-up and further refinement of transponders (passive or active functional structure) can be found, for example, in European patent EP 1 040 447 B1 or in European patent EP 0 762 535 B1.
The current state of the art in the realm of securing objects essentially describes devices for the explicit recognition of signal transmitters attached to objects as soon as these are located within a specified area.
U.S. Pat. No. 6,195,006 describes an inventory system with which articles that are loaned out to patrons are each provided with a transponder. At an article check-out counter, the signals emitted by the transponders as well as identification information of the patrons to whom the articles are checked out are then detected and transmitted to a database. The articles are returned at one or more return areas where the transponder signals of the returned articles are detected and transmitted to the database.
U.S. Pat. No. 5,745,036 describes an article security system for a store with which articles are provided with transponders that emit signals with identification codes of the articles. The system comprises several cash registers and a computer that stores identification codes of articles that have been paid for. In the store exit area, the identification codes are detected together with the date and time and, likewise indicating the date and time, video images are taken of the person transporting the articles. In order to recognize theft, the identification codes detected at the cash registers are regularly compared to the codes detected at the store exit and the corresponding video data is evaluated.